A typical gas turbine is configured from a compressor, a combustor, and a turbine. Air taken in through an air intake is compressed by the compressor, so that the air becomes high-temperature and high-pressure compressed air. A fuel is supplied to the compressed air, and the fuel and the compressed air are burned in the combustor, so that a high-temperature and high-pressure combustion gas (working fluid) is obtained. The turbine is driven by the combustion gas, and a generator coupled with the turbine is driven. The combustion gas that has driven the turbine is discharged as a flue gas from a discharge side of the turbine.
A control device that controls such a gas turbine executes temperature adjustment control operation of the gas turbine by adjusting an air amount and a supply amount of the fuel to be taken into the compressor so that a turbine inlet temperature of the turbine into which the combustion gas flows in does not exceed an upper limit temperature set in advance. This is because, while performance (work efficiency) becomes higher as the turbine inlet temperature is higher, it is difficult for high-temperature components around a turbine inlet to bear a heat load if the turbine inlet temperature becomes too high. To be specific, in the temperature adjustment control, the operation of the gas turbine is controlled such that the flue gas temperature from the turbine does not exceed a temperature adjustment line indicating an upper limit temperature of the flue gas temperature defined according to gas turbine state amounts such as a load (generator output) and a pressure ratio of the gas turbine. Here, the temperature adjustment line is defined as a mathematical function in which the upper limit temperature of the flue gas temperature becomes higher as the load of the gas turbine becomes smaller while the upper limit temperature of the flue gas temperature becomes lower as the load of the gas turbine becomes larger.
As the control device of the gas turbine, which performs the temperature adjustment control, there are ones described in Japanese Patent Publication No. 2008-75578 and Japanese Patent Publication No. 2007-40171. In an operation control device of a gas turbine of Japanese Patent Publication No. 2008-75578, an inlet guide vane is provided on an air-suction side of a compressor, and the degree of opening of the inlet guide vane is set according to a generator output from a generator output sensor on the basis of a relationship of the degree of opening of the inlet guide vane with respect to an output value of the generator. Further, in an inlet guide vane control device of a gas turbine of Japanese Patent Publication No. 2007-40171, an inlet guide vane is provided on an air-suction side of a compressor, and the degree of opening of the inlet guide vane corresponding to a generator output (gas turbine output) after correction of a sucked air temperature is set.